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The research of the neutron induced Single Event Effect (SEE) at aircraft altitudes or at ground level are very important since the neutron radiation is able to cause serious errors or damages on electronic components and system. TheWeapons Neutron Research (WNR) facility at Los Alamos Neutron Science Center (LANSCE), and ANITA (Atmospheric-like Neutrons from thIck TArget) facility at The Svedberg Laboratory (TSL) both provide spallation neutron source for radiation testing of electronic components. A local beam monitoring system was successfully developed by S. Platt and L. Zhang in the University of Central Lancashire for measuring neutron dosimetry during accelerated SEE testing of electronic devices with using silicon photodiode. However, such silicon photodiode is sensitive to gamma-ray as well. For above reasons, characterization of neutron and gamma fields at spallation neutron sources used for accelerated SEE testing has become the purpose of this work. Monte Carlo calculation of radiation fields at spallation neutron source was used to characterize neutron and gamma energy spectra for accelerated single event effect testing. Geant4 (GEometry ANd Tracking version 4) toolkit, using Monte Carlo method, was used to simulate a preliminary model of spallation neutron source at LANSCE (ICE House, WNR) and TSL (ANITA) for understanding physical mechanisms of neutron and gamma interactions with matter. At first, two preliminary spallation neutron sources on basis of WNR (ICE House) and ANITA facilities were modeled with using two intra-nuclear cascade models (bertini, binary) provided by Geant4 reference physics lists. The result of neutron spectrum with binary INC model agrees well with LANSCE measurement data and independent calculation results in each case. In this computation, gamma dose rates at WNR and ANITA were calculated, and gamma dose rate from the simulation is consistent with the ANITA measurement results. The results of photon energy spectra with using Geant4 toolkit presents a continuum between 0.1MeV and 10MeV, and the annihilation peak at 0.5MeV. However, calculation results of neutron spectrum at ANITA facility with using binary INC model match ANITA measurements less well in absolute neutron yield above 20MeV, which is likely due to the missing geometry components in preliminary spallation neutron source simulation. A more complex model of ANITA facility was constructed with adding bending magnet, shielding components, detector system, and collimator, which makes modelling as realistically as possible. The discrepancy in absolute neutron yield between simulation results and measurements data has improved at Standard User Position (SUP) of ANITA facility, in contrast with the preliminary modelling of ANITA neutron source. At the same time, a new position referred as Close User Position (CUP) was investigated in order to compare with ANITA measurement informed by Monte Carlo N-Particle eXtended (MCNPX) simulation results. The neutron spatial distribution, radius effect for neutrons, neutron beam profiles, and time of flight spectra were calculated at the SUP and CUP positions for different collimator apertures of 3 cm, 10.2 cm, and 30 cm, respectively. A comparison of simulated neutron beam profiles folded with 238U (n, f) cross-section with ANITA measurements at the SUP and CUP-TOF positions was used for validating improved ANITA neutron source modelling. The neutron beam profiles in the horizontal direction were predicted with using Geant4, which filled the gap of geometrical limitation at ANITA facility for accelerated single event effect testing. It is the first time to predict gamma dose rate at the SUP and CUP positions for 3 cm, 10.2 cm, and 30 cm collimators with using Geant4 modelling of ANITA neutron source. In addition, the gamma dose rate at the SUP position is consistent with ANITA measurement data. Finally, the gamma yield, photon spatial distribution, dose rate against energy are considered for gamma field at the SUP and CUP positions, which have contributed to understand and analyse gamma interactions with matter.

Preterm birth and the premature infant have been predominately studied from clinical perspectives. The experiences of parenting a preterm child and the experiences of staff directly involved in the care of preterm infants have been studied much less. Additionally, less is known about the meaning of experiences around the preterm infant’s discharge from the neonatal unit and life at home thereafter. This study addresses these gaps identified in research and aims to generate a deeper understanding of the meanings, and lived experiences of NICU-to-home transition from multiple perspectives: mothers and fathers, and neonatal staff. This is a Heideggerian hermeneutic phenomenological study of the experiences of Maltese parents of preterm infants and, of neonatal staff of NICU-to-home transition. Using purposive sampling, open interviews were conducted with 9 mother-father dyads of preterm infants and 12 neonatal staff that included midwives, nurses and doctors working on the only neonatal unit in Malta. A modified vignette technique based on the parents’ interviews was used to stimulate reflective talk with the staff. A longitudinal design was adopted for data collection from the parents: at 1 month, 3 months and 6 months after discharge of their baby from the unit. The research process including analysis of the data was guided by van Manen (1990). The parents’ experiences of NICU-to-home transition are represented through four main themes: ‘Shadowed by fading clouds of uncertainty’, ‘Reaching out’, ‘Watching vigilantly’ and ‘Living the new family’. In addition, three main themes emerged from the staff data: ‘Acknowledging good practice’, ‘Realising limits’ and ‘Awakening to needed improvements in care’. Findings indicate that, in the longer term in the home setting, parents translated their parenting approaches through the norms of neonatal unit routines and practices. Staff findings revealed that care focuses primarily on producing technically prepared parents in infant care which arises out of their sense of responsibility towards the babies’ wellbeing that extends to after being discharged from the neonatal unit. A further in-depth interpretation and synthesis of the findings was undertaken drawing on the philosophy of Heidegger (1962). This revealed ‘oscillating realities’ between parents’ and staff experiences, particularly in the degree to which they endeavoured to solicitude which ‘leaped in’ or ‘leaped ahead’, and the extent to which technocratic ways of Being permeated their relationships to each other and to the babies. Implications of the findings and suggestions for further research are presented.

In this PhD some key computational and algorithmic aspects of the Combined Finite Discrete Element Method (FDEM) are critically evaluated and either alternative novel or improved solutions have been proposed, developed and tested. In particular, two novel algorithms for contact detection have been developed. Also a comparative study of different contact detection algorithms has been made. The scope of this work also included large and grand scale FDEM problems that require intensive use of CPU; thus, novel parallelization solutions for grand scale FDEM problems have been developed and implemented using the MPI (Message Passing Interface) based domain decomposition. In this context a special attention is paid to the rapidly developing multi-core desktop architectures. The proposed novel solutions have been intensively validated and verified and demonstrated using various problems from literature.

The integration of biological and genetic data has established that diverse biological processes, involving multiple effectors, influence circulating levels of triglyceride and cholesterol. This diversity may underlie the genetic complexity of human dyslipidemias, including the common and highly atherogenic condition, Familial Combined Hyperlipidemia (FCHL). The aetiologies of FCHL are currently undetermined. In this thesis, a multi-pronged approach was employed to identify genes/variants contributing to the linkage observed between the chromosome 21q22.2-22.3 interval and lipid traits, in white-British FCHL families. Additionally GPIHBP1, which encodes glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1, was studied. GPIHBP1 represents a strong FCHL candidate gene due to its role in the lipolytic processing of triglyceride-rich lipoproteins. Combined genetic and gene expression analyses, focussed upon a refined 3.8Mb interval on chromosome 21q22.3 that was linked to lipid abnormalities in subsets of FCHL families, identified two genes (COL18A1 and PKNOX1 ) that warrant further investigation with regard to their contribution to FCHL. Promising results were also obtained for C21orf57, which resides just outside the 3.8Mb interval. Genetic association analyses in 1725 members of 239 FCHL families identified nominal association (P=0.0009) between a TSPEAR variant, rs34163868, and plasma triglyceride levels. Furthermore, transcript levels of CBS and TRPM2 were significantly altered by treatment with the PPAR-agonist bezafibrate in a rat hepatoma cell line, thus implicating these genes in triglyceride/fatty acid metabolism. In combined analysis of five independent cohorts, the minor allele of the GPIHBP1 variant, rs11538388 was protective against hypertriglyceridemia (P=2.98x10-4). The same allele was associated with decreased risk of coronary heart disease in the prospective Northwick Park Heart Study II (hazard ratio for carriers=0.76, P=0.0480) and delayed age of onset in the Southampton Atherosclerosis Study (odds ratio=0.76, P=0.0146). Collectively, these data demonstrate that the rs11538388 minor allele, or variant in linkage disequilibrium, is associated with more favourable processing of atherogenic lipoproteins.

by Chan Chi Wai, Angus. / "Submitted in Jan 1999, revised in Jan 2000." / Thesis (M.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (p. 262-294). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

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Trichodesmium is a globally significant marine diazotroph responsible for supplying new nitrogen to the oligotrophic regions in which it is found. Though it has been studied for decades, our understanding of the ways in which environmental factors can affect its nitrogen fixation rate remains limited. A continuous culture of Trichodesmium was established in which steady state growth and nitrogen fixation were maintained at dilution rates ranging from 0.27 to 0.67 d-1. Our results clearly show that, as growth rate increased, biomass decreased linearly and nitrogen fixation rate increased linearly. C:N:P ratios remained constant over the range of growth rates studied, suggesting a tight coupling between macronutrient uptake and the maintenance of balanced growth at steady state. We used cultures at steady state to determine the impact of nitrate exposure and uptake on nitrogen fixation. Nitrate inhibits nitrogen fixation by up to 70% in a concentration-dependent manner at initial nitrate concentrations less than 10?? Nitrate uptake accounted for as much as 86% of total N uptake and, at initial nitrate concentrations greater than 2.5 ??more than made up for the observed inhibition of nitrogen fixation. A field study of this diazotroph shows that nitrogen fixation scales with light intensity from a maximum at 50% surface irradiance. Estimated areal nitrogen fixation rates in the Gulf of Mexico, based on vertical abundance profiles and the relationship between nitrogen fixation and surface irradiance, are comparable to measurements made in other oligotrophic regions. Stable isotopic composition of the particulate organic matter and the zooplankton confirms that Trichodesmium nitrogen and carbon are moving into the food chain and are important to higher trophic levels. As much as 60% of the zooplankton carbon was derived from Trichodesmium. Our work established that this diazotroph is ecologically important in the water column of the Gulf of Mexico, with important implications for nitrogen and carbon cycling. Findings from our field and culture studies can be added to models used to quantify the importance of Trichodesmium nitrogen fixation on an oceanic scale.

In considering the global power generation industry, fossil fuel power plants still dominates where LNG presents one of the major clean fuel source. Although Taiwan remains as one of the main importers of LNG in the world, the cold energy was not utilized effectively which only accounts for 8% of total. Especially, the hot and humid local climates caused the Gas turbines to work under low efficiency which presents significant room for improvement when inlet cooling technology was imposed. In this research, the inlet cooling process using mechanical chillers, absorption chillers, and LNG cold reclaim technology were simulated using the Thermoflex software in a tpical combined cycle environment. The waste heat from the power plant was further utilized for Sea water desalination purposes under MED process. Simulation result indicated that , in using 2% of the waste heat from the plant, and produce 60 tons per hour of fresh water , at the cost of power output reduction of 1 %. Further simulation result also validated the economic feasibility which warranted engineering application potentials.